There’s some other author named Goudge out there (a distant cousin or niece of some sort), but Elizabeth Goudge is the one we’re concerned with. She made her name with Green Dolphin Street (which became a justly famous Hollywood movie and a famous jazz tune). But she wrote a good many other novels after that.
Most of her novels are historicals, though some were contemporary to her time of writing. They tended to be set in the English countryside or in small old towns. The past tends to be a constant presence. Emotions run deep but don’t show up right away. Sometimes things slip into fantasy. Generally things are either cozy or terrifying, and there’s not much warning of either. She was a favorite of J.K. Rowling, among many other fans of note, but hasn’t gotten much reprinting. Out of her extremely prolific output, I’ve seen about ten of her books and that’s all.
So I’m surprised that anybody filmed the influential but deeply odd fantasy The Little White Horse. I’m even more surprised that they filmed it under the title The Secret of Moonacre, but so it is. Your man Ioan Gruffudd and your man Tim Curry are both in it.
When it comes to reprints, there are a few US editions these days, but mostly you’ll have to look to libraries, used book purveyors, and aged relatives. In the UK, the situation is not much different, alas.